SQL was revised in 1992, and that version is known as SQL2. It was again revised in 1998 to become SQL3. SQL3 supports objects, which weren't previously supported in other versions, but as of late 2001, few if any database management systems implement SQL3.
SQL, although defined by ANSI, has many variations and extensions, most of which are of a proprietary nature, such as Oracle Corporation's PL/SQL or Sybase?'s [Transact SQL]?.